Means for transmitting signals for wireless telegraphy



"l1/umh 11 1924. 1,486,134

H. GYERDIEN MEANS FOR TRANSMITTING `SIGNALS FOR WIRELESS TELEGRAPHY Fliled Nov. 30, 1921 I.-a, I

I 0 .if l v 5 Patented Mar. 11, 1924.

UNITED STATES PATENT orales.

mms GERDIEN, or BERLIN-SCIIMAEGENDORE, GERMANY, AssIGNoR 'ro SIEMENS HALSKE, AKTIENGESELLSCHAFT, or sIEMENssTAnT, NEAR BERLIN, GERMANY, n

CORPORATION OF GERMANY. y

MEANS EoR 'rRANsMITfrING sIGNALs FOR WIRELESS TELEGRAPIIK Application filed November 30, 1921. Serial No. 518,846.

-To all whom it may concern.'

Be it known that I, I-IANS GERDIEN, a citizen of the German Empire, residing at Berlin-Schmargendorf, Germany, have invented certain *new and useful Improvements in Means for Transmitting Signals' for Wireless Telegrapliy, of which the following is a specification. Y

In the transmission of Morse signals for wireless telegraphy, the interruption of the antenna energy is connected with diiiiculties owing to its high voltage. Thus, it is more preferable to untune the antenna when the signals cease, so that it' ceases to take-up energy. For the purpose of untuning the antenna in a simple manner, it is fitted with a self-induction having' an iron core. The

amount of self-induction .is changed by a change of the saturation of the iron, which can be easily attained by continuous current of ordinary voltage. The antenna is, for

instance, tuned if the iron core is excited by the continuous current field', and untuned if the continuous current field disappears. To transmit a Morse signal, thus, a continuous current need to be sent only through a separate winding of the self-induction coil.

According to the present invention, an increased voltage is temporarily-used for the excitation of said continuous current field. Thereby, a quicker formation of the continuous current field and thus sharp signals are obtained. Correspondingly, the vanishing of the field can be artificially accelerated. Such and similar means for a quick excitation and dissipation of continuous current fields are already known in the art in connection with other branches of the electro-technical industry, for instance with dynamos and electromotors. For the transmission of signals for Wireless telegraphy, said means have the particular advantage that the signalsA can be quickly started with full energy and again sharply cut off, which is of great importance for a good understanding at large distances. By the improvement according to the present invention, besides, the utilization of radiotelegraphic plants is considerably increased, for the quicker the antenna is fully energized at the ,Start of a signal, the shorter may be the latter, andthe higher may be the transmitting speed. There existsv a particular necessity for an increase ofthe latter in case the Morse'key is not loperated by hand but mechanically by means of a perforated tape.

Preferably, the increased voltage for an acceleration of thel excitation 'and de-excitation may be supplied through a condenser. In this case, one can work with very high voltages Without dangertoj the conductors and coils, owing lto the energy stored in the condenserV beingalmost consumed as soon as its object has been accomplished.

In the accompanying drawing:

Fig. l shows the connection diagram of one appropriate example of'putting the invention vinto* practice,

Fig. 2 shows, diagrammatically,l the flow of current. l

Fig'. 3 shows a modification in similar to Fig 1.

Referring to Fig. 1:-In 'the circuit' of the antenna 2, a coil 32 is located and Wound around a closed iron core l, which, besides, carries a coil 30 and a coil 3. The coil 30 is connected with a high-frequency machine 31. Alever 5 serves Jfor transmitting the Morse signals, said lever-being held in its inoperative position (shown) by means of a spring 58, in which position it closes, by means of an insulated contact plate 33, the contacts 10, by means of which the condenser 8 isv connected with the high-voltage source 9. Upon depressioni of the lever 5,v it strikes upon afcontact7 andslides along the latter until it reaches in fits end position also the contact 6. The fulcrum 49 of said lever is conductively connected with one end of the coil 3. The contact 7 is connected to one side of the condenser 8 and the contact 6 is connected to one pole cfa continuous current source 4 the other pole of which is connected with the coil 3. From the same terminal of the coil 3v leads a conductor 34 over the ohmic resistance 35 tothe other side of condenser 8.

An electrmagnet 40 serves for operating the lever 5, one coil terminal of the former being connected through a conductor 36 with the current source 41. A conductor 37 leads treni source 411v to a bracket 42, on

sage of current between'rollers 43 and 44,r

unless'a perforation therein appears between them, when such passage becomes possible.v TheV device works as follows z-'The capacity-in the circuit of the antenna 2a nd itsy self-induction, kof whi'chthe coil 32 withA the vmagnetic circuit 1l forms an essential part, are so equalized that the natural fre quency of the antenna circuit cor-responds to the periodicity of the high-frequency machine 31, which is the case when the cur-- rent of the continuous current source 4 flows through the coil y3. The 'antenna 2 'is then fully energized owing to thel syntony between said frequencies. 'ln the inoperative position of lever 5 shown, however, current does not ow through the coil 3. The iron of the magnetic circuit 1 is then not saturated, the self-induction of the coil 32 is essentially increased, and the naturalfrequency of the antenna circuit 2 does not correspond to the periodicity of the high-frequency machine 31. The antenna does, therefore, take-up no energy. As soon as, then, by a rotation of the spool 48, theV perforated tape46 is set in motion anda perforation therein appears between the contact rollers 43 ,and 44, a current flows from the current source 41 over the conductor 37, the bracket 42,

- the contact rollers 43 and ,44, the conductor 38, the electromagnet 40,A and the conductor 36, back to the current source 41. Consequently, the lever 5 is attracted, it closing first the' contact 7. Thereby, a rush of current flows from the condenser 8 through the resistance 35 andthe Vconductor 34 into the coil 3 and hence through the fulcrum' 49 of the lever 5, the latter itself, and the contact 7, back to the condenser 8. The capacity ofk said condenser and its charging potential are so chosen that said rush of current suffices to produce the desired saturation in the iron core 1. At the moment when the latter has beenattained, also the lever 5 has reached the contact 6. Through the latter, the current source 4 is connected with the coil 3, and the formerm'aintains now the magnetization current in the coil 3. As described, dueto the saturation of the iron core 1, the antenna 2 is tuned to resonance `and takes-up full energy. As soon as the perforated tape 46 interrupts again the contact between the` contact rollers 43 and 44, the electromagnet 40 becomes cursupplied from the battery 4,the intensity of which is represented by the Vhorizontal upper part of the curve 1. The dotted part ofthe curve I shows, for sakeoff completeness, how the condenser current woiild fiow if the circuit through the battery 4 would not be olosedrrfhe curve H shows, further, the ascentv of the current which would take place with a connection of the current source 4to the coil 3 without'the employ'-l ment of a condenser. Whereas, in thelatter case, the full magnetization f current would not yet be attained in 0,3 seconds, it is attained by the highvcltage of the condenser in less than 0,003 seconds. The charging potential of the condenser is, in this example, chosen`130` times asiarge as the voltageof the battery `4. i

To prevent vibrations being produced in the circuit formed of the condenser y8 and the Ycoil 3, the resistance 3 5, which has" no self-induction, is inserted in said circuit., In spite of the high voltage ofthe current source 9, the construction ofthe vcontacts 10 and 33 offers no dihculty, owing to their interruption taking place always in currentl less condition only.

Instead of by the electromagnet 40, vthe lever' 5 may also beoperated by hand." Generally, the eect would then not be so com# plete, since a manipulatoryr depression cannot be so exact to the proper speed, so that it might easily occurtthat the contact 6 is closed too late, e. g., the current source 4 is connected with the coil 3 when the mag-V netization current produced by the con-l denser 8 is already again decreased. Thev Morse signals would then not be so sharp as when working Witha kperforated tape.l

However, also with a telegraphingy by hand the required period between the put? ting-in of the permanent current. source 4 and that .of the condenser Vcan be 'exactly maintained with the employment of the diagram of connection shown in Fig. 3. 1n this example, also provision is made for arv shortening of the de-eXcitation time. The Morse key 13 is to' be operated by the hand of a telegraphist. Upon depression of said key, current is sent from the battery 14v` through the relay magnet 12, which actuatesv a contact lever 11, the latter being coupled by a rod 50 to the contact levers 51, 52, v53, 54. With currentless magnet 12, all said contact levers are kept in their inoperative position (shown) by means of'springs 11a, 51a,-

52, 53a, 54a, the contacts 15, 16, 20 and 21 being then closed. Upon attraction of the lever 11 by the magnet 1 2, the contacts lastmentioned are openedand the contacts 17, 19, 22, 23 and 24 are closed. The contacts 22 and 23 are reached by their levers 52 and 53 directly after starting of said movement, and the other contacts at the terminationof said movement only. The fulcra of the contact levers 51 and 54 are connected with the two sides of a condenser 18. The electric connection of the latter leads on one side through the-lever 54 and the contact 16 to one terminal 57 of the coil 3 and on the other side through the lever 51, the contact 15, and the ohmic resistance 35 to the other terminal 58 of said coil 3. The fulcra of the levers 52 and 53 are connected with the condenser 8. The electric connection of the latter leads on one side through the lever 53 and the contact 21 to one pole 59 of the high-voltage source 9 and on the other side through the lever 52 and the contact 20 to the other pole 60 of said high-voltage source 9. If, with excited magnet 12, the levers assume their operative positions, the condenser 18 is connected over the switch 54 and the contact 19 with the pole 60, and over the switch 51 and the contact 17 with the'pole 59, of the current source 9, while the condenser 8 is connected over the switch 53 and the contact 23 with the terminal 57, and over the switch 52, the contact 22 and the ohmic resistance 35 with the terminal 58, of the coil 3, the lever 11 closing the contact 24 and connecting thus the current source 4 with the coil 3.

The operation of the device last-described is as follows As soon as the telegraphist intends to transmit a signal, he depresses the key 13. Consequently, the magnet 12 is excited and contact levers 51-54 are moved downwards. Thereby, first the connections of the two condensers 8 and 18 are interrupted. Then, the condenser 8 is connected through the contacts 22 and 23 to the coil 3, the latter magnetizing thereby the iron core 1. As soon as the induction in the iron core has attained a certain value, the antenna 2 is tuned to resonance with the high-frequency machine 31 and takes-up full energy. The speed, with which the lever 11 is attracted, is so determined that at this moment also the contact levers have reached their end positions. Consequently, at this moment the current source 4 is connected over the contact 24 with the coil 3 and maintains here the magnetization current.l Besides, the contact levers 51 and 54 connect the condenser 18 with the highvoltage source 9.

When the telegraphist releases the key i13,

neutralization of the continuous current ieldr is discharged into said condenser. When the contact levers reach their end positions, the condenser` 18 is connected over the contacts V15 and 16 with the continuous current coil 3, but with a polarity opposite to thatvv of the previously connected condenser 8. The capacity of the condenser 18 is so determined that its energy just sufiices to neutralize, as quickly as possible, the continuous current field still existing in the iron core 1. Furthermore, the condenser 8 is connected over the contacts 20 and 21 with the high-voltage source 9 and thus re-charged by the latter. In this example, the ohmic resistance 35 prevents electric oscillations being produced between the condensers and the coil 3.

It is immaterial for the essence of the present invention whether the antenna is tuned with unexcited continuous current ield or, as assumed in the connection*dia grams shown, with a saturation of the iron core 1.

1. Means for transmitting radio signals through an antenna, comprising an iron core having a coil, connected into the antenna circuit, a generator adapted to permanently supply radio frequency currents, a second coil onsaid iron core connected to said generator for supplying current to the antenna, a direct current coil on said iron core, means for supplying low potential direct current to said coil to vary the saturation of said` core for tuning and detuning the antenna during the signaling operation, and a separate source of high potential direct current, and means for connecting it to said direct current coil for quickly raising the saturation of said core to the desired point before the low` potential direct current supply is connected to said coil.

2. Means for transmitting radio signals through an antenna, comprising an iron core having a coil, connected into the antenna circuit, a generator adapted to permanently supply radio Jfrequency currents, a second coil on said iron core connected to said generator for supplying current to the antenna, a direct current coil on said iron core, means for supplying low potential direct current to said coil to vary the saturation of said core for tuning and detuning the antenna during the signaling operation, and a condenser, a source of high potential direct current for charging said condenser and means for connecting the charged c011- denser to said direct current coil for quickly raising the saturation oi said core to the desired point bei'ore the loW potential direct current supply is connected to said coil.

3. Means for transmitting radio signals through an antenna, comprising an iron core having a coil, connected into the antenna circuit, a generator adapted topermanently supply radio frequency currents, a second.

coil on said iron core connectedto said generator for supplying current to the antenna, a direct current coil onsaid iron core, means for supplying low potential direct current to said coil to Vary the saturation of said core for tuning and detuning the antenna duringv the signaling operation, and a condenser, a source of high potential direct current for charging said condenser and means controlled by the 10W potential current supply means for connecting the charged condenser to said direct current coil for quickly raising the saturation of said core to thel desired point before the low potential direct current supply is connected to said coil.

In testimony whereof I aiiiX my signa- 25 ture.

HANS GERS'DIEN. 

